Of all the Hobie accessories, there are four that I wouldn't want to do without. They are the Large Rudder, Turbofins, Standard Cart and inflatable i Comfort Seat.
The Large Rudder, having twice the area of the standard rudder, offers vastly superior response and performance. It requires far less tweaking of the rudder control, almost zero-speed authority and is a must for all sailing activity and wake riding. It's like getting a set of performance tires on your car! At $23, it delivers the most bang for the buck.
Version 2 (shown) is easily identified by the notched leading edge for improved helm balance. V-1 is still available for the inflatables and for those who want to do some custom rudder mods.
ST Turbofins (shown below, right) not only add at least a 20% thrust potential, but IMO are more efficient than standard fins. It feels like you just got a major engine upgrade for your car. They also improve sailing performance by serving as larger "daggerboards". Some folks think they are harder to push -- they are if you're using the same cadence, but you can make the boat go the same speed with a slower, more relaxing pace. Not only do they give a higher cruising speed but offer substantially better acceleration for emergencies and wake rides. They can also improve the boat's turn radius slightly when held straight down.
Version 2 of the Turbofins has been out for a year now. They look the same but are a little more flexible, slightly easier to push and much more resistant to abrasion (but still not quite as tough as standard fins). Turbos can be hard on some of the older drives for "power users" but any Drive that has been upgraded to '08 drums and chain/cables and '09 sprockets and masts should have no issues. For most users though, any of the Drives are fine with the Turbos. ST fins (my wife's favorite), which are a shorter version of the Turbofins are almost as efficient, not quite as fast but easier to push at a faster cadence.
The Standard Plug-In Cart is a great back saver. When my boat hits the deck the cart is already strapped on and is not removed until the boat is in the water. All gear gets tossed in the boat so that only one trip to the water is necessary. The cart travels with the boat so it is ready to plug in prior to pulling out, and falls off conveniently when the boat is lifted back on the vehicle. With it you can park some distance from the launch area and easily walk your boat to the water. It can also be used as a "parking brake" as an alternative to beaching your boat when going ashore for an interim period -- saves scratches on the hull and sand in your Drive. It can accommodate up to 140# (tandem plus gear and ballast for solo outings) and is rugged, having been dropped regularly and drug through everything. It may not work as well as the Trax cart in soft sand, but is easier to pull in all other situations and will never get a flat tire! When I think about all the places I used to carry my boat and the extra trips with gear, I fully appreciate the difference this cart makes! Shown below with extensions to accommodate the tennis balls (concentrates the weight under the scuppers to eliminate the hull dent that otherwise appears).
Last but certainly not least, the i Comfort Seat is a real sleeper! Now whenever I try out a different boat, my fins and seat go with me. I used to get a sore butt after about 1/2 hour pedaling; now I just don't get one at all. Sailing, when you "hike" from one side of the cockpit to the other, it doesn't fold or buckle like the current standard seat. I've become so spoiled by this luxurious pad that I have little tolerance for the standard seat bottoms now, sorry to say. The pad can be adapted to all Hobie seats except the very old riveted seats.
I also enjoy a number of other Hobie accessories, but these are the ones I consider most essential for improving the handling, performance, convenience and comfort of basic Hobie kayaking.
